Castle to the Seaside

Castle to the Seaside enters the battlefield tapped unless you cast two or more spells this turn.
{t}, tap another untapped land: Add {u}{u}.
Whenever a creature with power 4 or greater
attacks you or a planeswalker you control, you
may have Castle to the Seaside become a 0/6
Giant Golem artifact creature with reach until
end of turn. It's still a land.